Interaction of the Joining Region in Junctophilin-2 With the L-Type Ca(2+) Channel Is Pivotal for Cardiac Dyad Assembly and Intracellular Ca(2+) Dynamics.
Interaction of the Joining Region in Junctophilin-2 With the L-Type Ca(2+) Channel Is Pivotal for Cardiac Dyad Assembly and Intracellular Ca(2+) Dynamics.
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DOI：
10.1161/circresaha.119.315715
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发表时间：
2021-01-08
影响因子：
20.1
通讯作者：
Houser SR
中科院分区：
文献类型：
--
作者：
Gross P;Johnson J;Romero CM;Eaton DM;Poulet C;Sanchez-Alonso J;Lucarelli C;Ross J;Gibb AA;Garbincius JF;Lambert J;Varol E;Yang Y;Wallner M;Feldsott EA;Kubo H;Berretta RM;Yu D;Rizzo V;Elrod J;Sabri A;Gorelik J;Chen X;Houser SR
正常心脏中Ca 2+诱导的Ca 2+释放（CICR）需要横小管（T-小管）内的L-型钙通道（LTCC）和连接肌浆网（jSR）内的Ryanodine受体（RyR）的紧密接近。CICR在心脏肥大和心力衰竭中被破坏，这与T-小管的损失和心脏二分体的破坏有关。在这些条件下，LTCC从T-小管重新分布以破坏CICR。负责LTCC募集到T-小管和从T-小管募集LTCC的分子机制尚不清楚。嗜连接蛋白-2（JPH 2）使T-小管和jSR之间紧密结合，以确保有效的CICR。JPH 2具有所谓的连接区域，其位于与T-管状质膜相互作用的结构域附近，LTCC被容纳在该结构域中。这种连接区域直接与LTCC相互作用并有助于LTCC募集到T小管的想法是未知的。确定JPH 2中的连接区域是否通过心肌细胞中的直接分子相互作用将LTCC招募到T-小管，以实现有效的CICR。在体内左心室肥厚和培养的成年猫和大鼠心室肌细胞中研究了JPH 2的丰度和LTCC的重新分布。蛋白质相互作用研究表明，JPH 2中的Joining区域与LTCC-α1C亚基相互作用，导致LTCC分布到二联体中，并与RyR共定位。在连接区（mutPG 1 JPH 2）中具有诱导突变的JPH 2引起T-小管重塑和二分体损失，表明LTCC和JPH 2之间的相互作用对于T-小管稳定是至关重要的。mutPG 1 JPH 2可引起β-肾上腺素能刺激后钙释放的不同步，同时兴奋-收缩（EC）偶联受损。在mutPG 1 JPH 2过表达的心肌细胞中，Ca 2+调节受到干扰，导致钙/钙调素依赖性激酶-II激活，并改变了心肌细胞的生物能量学。LTCC和JPH 2中的Joining区域之间的相互作用促进二分体组装并维持心肌细胞中的正常CIRC。
Ca2+ induced Ca2+ release (CICR) in normal hearts requires close approximation of L-type calcium channels (LTCCs) within the transverse tubules (T-tubules), and Ryanodine receptors (RyR) within the junctional sarcoplasmic reticulum (jSR). CICR is disrupted in cardiac hypertrophy and heart failure, which is associated with loss of T-tubules and disruption of cardiac dyads. In these conditions, LTCCs are redistributed from the T-tubules to disrupt CICR. The molecular mechanism responsible for LTCCs recruitment to and from the T-tubules is not well known. Junctophilin-2 (JPH2) enables close association between T-tubules and the jSR to ensure efficient CICR. JPH2 has a so-called Joining region that is located near domains that interact with T-tubular plasma membrane, where LTCCs are housed. The idea that this Joining region directly interacts with LTCCs and contributes to LTCC recruitment to T-tubules is unknown. To determine if the Joining region in JPH2 recruits LTCCs to T-tubules through direct molecular interaction in cardiomyocytes to enable efficient CICR. Modified abundance of JPH2 and redistribution of LTCC were studied in left ventricular hypertrophy in vivo and in cultured adult Feline and rat ventricular myocytes. Protein-protein interaction studies showed that the Joining region in JPH2 interacts with LTCC-α1C subunit and causes LTCCs distribution to the dyads, where they colocalize with RyRs. A JPH2 with induced mutations in the Joining region (mutPG1JPH2) caused T-tubule remodeling and dyad loss, showing that an interaction between LTCC and JPH2 is crucial for T-tubule stabilization. mutPG1JPH2 caused asynchronous Ca2+-release with impaired excitation-contraction (EC) coupling after β-adrenergic stimulation. The disturbed Ca2+ regulation in mutPG1JPH2 overexpressing myocytes caused Calcium/calmodulin-dependent kinase-II activation and altered myocyte bioenergetics. The interaction between LTCC and the Joining region in JPH2 facilitates dyad assembly and maintains normal CIRC in cardiomyocytes.